Help I Messed Up The Dummy Cake

I have a wedding today and realized when it was to late that I had done the bride's dummy cake in round shape instead of a hexagon shape. The wedding is tonght at 6:30 and I have no where to get hexagon shaped dummies in time. The bride is also having kitchen cakes which were made exactly to the bride's specifications.

Do I give the bride a full refund on the dummy cake and just charge for the kitchen cakes. I feel that this is what is right since I messed up on the shape. What would you do?